77 resultados para Ditches.
Resumo:
The molluscicidal evaluation of Euphorbia splendens var. hislopii (Crown of thorns) against Lymnaea columella snails, intermediate host of Fasciola hepatica, in irrigation ditches of the Pisciculture Station at Universidade Federal Rural do Rio de Janeiro, was studied under limited field conditions. An aqueous solution of the latex at 5 mg/l was tested in two irrigation ditches (experimental and control ditches), after initial sampling of the snail population present. Twenty-four hours after application of the product, it was verified that 97.4% of free L. columella snails and 100% of snails of the same species captive in cages and used as sentinels at three points equidistant from the application site in the experimental ditch, died. For Biomphalaria tenagophila and Melanoides tuberculata snails, present in the experimental ditch, the mortality was 100%, for the species Pomacea spp. the mortality was 40%. No mortality was verified in the free mollusks, or in the sentinels in the ditch used as control. E. splendens var. hislopii latex is thus an efficient natural molluscicide, which may be used as an alternative control agent against L. columella.
Resumo:
The development of palaeoparasitology in Japan has occurred in recent decades. Despite the fact that archaeology in Japan has been slow to develop techniques for excavating ancient toilets, important information about the development of sanitation has been derived from the analysis of a few sites. This shows that the earliest people had very simple methods of sanitation. As populations increased, sanitation became more complex. Ditches surrounding early towns were used for excrement disposal. Eventually distinct toilets were developed followed by cesspit type toilets and flushing toilets. The parasites recovered from these toilets include many species that infect humans today. These parasite spectra reflect local use of aquatic, marine, and land animals. Fecal borne disease was an increasing problem as represented by whipworm and ascarid roundworm eggs. Interestingly, ascarid roundworms were absent in the earliest cultures and only became common with rice agriculture. Finds of pollen and seeds in toilet sediments reveal the use of medicinal plants to control the emerging problem of parasites.
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This study focuses on the geographic distribution of the snail of the genus Biomphalaria and evaluates its infectivity by Schistosoma mansoni in 5264 specimens collected in the municipality of Juiz de Fora, Minas Gerais, Brazil. Of the 31 locations studied, 6 were reservoirs, 11 rudimentary holding ponds, 7 irrigation ditches, 5 lakes, 1 ornamental pond, and 1 waterfall. Intermediate hosts were found only in the rudimentary ponds and ditches, which were 100% positive. Using morphological and molecular analysis techniques, B. tenagophila, B. peregrina, and B. straminea were identified. This is the first report of B. stramínea in the municipality, and evaluation of its infective potential revealed susceptibility of 25.4%. Although we did not find specimens of Biomphalaria infected by S. mansoni, the data obtained indicate the presence of intermediate hosts, especially in the irrigation ditches in Juiz de Fora, and their proximity to contaminated areas.
Resumo:
The object of the present work was to identify the larval habitats of Culex eduardoi and to determine the microenvironmental conditions related to their presence in different artificial freshwater environments (temporary, semi-permanent, irrigation ditches, and drainage ditches) in tillable areas of Chubut Province, Argentina. This report represents the first record of Cx. eduardoi from this Province and extends its range to latitude 45°S. Immature stages of Cx. eduardoi were found in 8 out of 109 (7.3 %) freshwater habitats and were significantly more prevalent in semi-permanent water bodies. Positive sites had significantly larger surface areas and more vegetation cover than negative sites.
Resumo:
L’objectiu d’aquest article és fer una aproximació al procés històric de creació dels anomenats “paisatges de l’aigua” a la plana de l’Alt Empordà. En primer lloc, es presenten els principals elements que configuren els paisatges de l’aigua a la plana (els rius, les rieres, els aiguamolls, els estanys, les sèquies, canals de regadiu, etc.). A continuació, s’analitza el procés històric de creació dels paisatges de l’aigua a la plana de l’Alt Empordà a través d’un discurs que s’ha simplificat en dues grans etapes: una llarga etapa caracteritzada per la lluita mantinguda per la societat altempordanesa contra l’aigua i, una segona etapa, molt més recent, on els esforços d’aquesta societat es concentren en l’obtenció d’aquesta aigua. Per últim, s’analitza en detall aquest procés a partir del cas concret del paisatge configurat per les closes
Resumo:
The aims of this study were to characterise the ground-level larval habitats of the mosquito Culex quinquefasciatus, to determine the relationships between habitat characteristics and larval abundance and to examine seasonal larval-stage variations in Córdoba city. Every two weeks for two years, 15 larval habitats (natural and artificial water bodies, including shallow wells, drains, retention ponds, canals and ditches) were visited and sampled for larval mosquitoes. Data regarding the water depth, temperature and pH, permanence, the presence of aquatic vegetation and the density of collected mosquito larvae were recorded. Data on the average air temperatures and accumulated precipitation during the 15 days prior to each sampling date were also obtained. Cx. quinquefasciatus larvae were collected throughout the study period and were generally most abundant in the summer season. Generalised linear mixed models indicated the average air temperature and presence of dicotyledonous aquatic vegetation as variables that served as important predictors of larval densities. Additionally, permanent breeding sites supported high larval densities. In Córdoba city and possibly in other highly populated cities at the same latitude with the same environmental conditions, control programs should focus on permanent larval habitats with aquatic vegetation during the early spring, when the Cx. quinquefasciatus population begins to increase.
Resumo:
This manual describes best roadway maintenance practices for Iowa's local roads and streets, from the center line to shoulders, ditches, and drainage, with chapters on public relations, bridge maintenance, and snow and ice control. Each chapter contains safety tips, information(as appropriate) on managing quality control, and a list of references for further information.
Resumo:
PURPOSE: Recent work practices in the conservation and restoration involve the use of cyclododecane (CDD, CAS 294-62-2) to protect fragile artifacts during their handling or transportation. Little is known about its toxicity, and no previous exposure has been reported. A short field investigation was conducted to characterize the exposure conditions to both CDD vapors and aerosols.METHODS: Measurements were conducted in the laboratory of conservation and restoration of the archeological service in Bern (Switzerland). Three indoor and four outdoor typical work situations, either during brush or spray gun applications, were investigated. Measurements were performed on charcoal adsorbent tube and analyzed by a gas chromatograph equipped with a flame ionization detector.RESULTS: Measurements have been conducted during both brush and spray gun applications. Indoor exposures were of 0.75-15.5 mg/m(3), while outdoors exposures were 19.5-53.9 mg/m(3). Exposures appear to be extremely localized due to both physicochemical properties and application methods of the CDD. Vapor exposure increases dramatically with the confinement of the workplace.CONCLUSION: Preventive measures should be undertaken to limit as much as possible these exposures. Field work in confined areas (ditches, underground) is of particular concern. CDD-coated artifacts or materials should be stored in ventilated areas to avoid delayed exposures. [Authors]
Resumo:
The DOT is in the process of replanting all the roadsides on state primary highways to native grasses and wildflowers. While the existing vegetation may look nice, it is not functioning as well as needed for roadside purposes such as erosion control, water infiltration or weed competition. The DOT currently spends nearly $3 million each year to clean ditches, remove silt, and spray and mow weeds. The DOT believes the native vegetation, once established, will provide sufficient benefits and reduced maintenance costs to warrant replacing the existing vegetation.
Resumo:
Freezing and thawing action induces damage to unbound gravel roads in Iowa resulting in maintenance costs for secondary road departments. Some approaches currently used by County Engineers to deal with this problem include temporarily spreading rock on the affected areas, lowering or improving drainage ditches, tiling, bridging the area with stone and geosynthetic covered by a top course of aggregate or gravel, coring boreholes and filling them with calcium chloride to melt lenses and provide drainage, and re-grading the crown to a slope of 4% to 6% to maximize spring drainage. However, most of these maintenance solutions are aimed at dealing with conditions after they occur. This study was tasked with identifying alternative approaches in the literature to mitigate the problem. An annotated bibliographic record of literature on the topic of frost-heave and thaw-weakening of gravel roads was generated and organized by topic, and all documents were assessed in terms of a suitable rating for mitigating the problem in Iowa. Over 300 technical articles were collected and selected down to about 150 relevant articles for a full assessment. The documents collected have been organized in an electronic database, which can be used as a tool by practitioners to search for information regarding the various repair and mitigation solutions, measurement technologies, and experiences that have been documented by selected domestic and international researchers and practitioners. Out of the 150+ articles, 71 articles were ranked as highly applicable to conditions in Iowa. The primary mitigation methods identified in this study included chemical and mechanical stabilization; scarification, blending, and recompaction; removal and replacement; separation, and reinforcement; geogrids and cellular confinement; drainage control and capillary barriers, and use of alternative materials. It is recommended that demonstration research projects be established to examine a range of construction methods and materials for treating granular surfaced roadways to mitigate frost-heave and thaw-weakening problems. Preliminary frost-susceptibility test results from ASTM D5916 are included for a range of Iowa materials.
Resumo:
In 1975, Kossuth County had 492 miles of asphalt pavements, sixty percent of which were between l5 and 20 years old. Many of these roadways were in need of rehabilitation. Normally, asphaltic resurfacing would be the procedure for correcting the pavement deterioration. There are areas within the state of Iowa which do not have Class I aggregate readily available for asphalt cement concrete paving. Kossuth County is one of those areas. The problem is typified by this project. Limestone aggregate to be incorporated into the asphalt resurfacing had to be hauled 53 miles from the quarry to the plant site. The cost of hauling good quality aggregate coupled with the increasing cost of asphalt cement encouraged Kossuth County to investigate the possibility of asphaltic pavement recycling. Another problem, possibly unique to Kossuth County, was the way the original roadways had been constructed. A good clay soil was present under 3 to 4 feet of poorer soil. In order to obtain this good clay soil for subbase construction, the roadway ditches were excavated 1 to 3 feet into the clay soil layer. The resultant roadway tops were several feet above the surrounding farm land and generally less than 26 feet wide. To bring the existing roadway up to current minimum design width, there were two choices: One was to widen the roadway by truck hauling soil and constructing new 4 to 6 foot shoulders. The cost of widening by this method averaged $36,000 per mile in 1975. The other choice was to remove the old pavement and widen the roadway by lowering the grade line. The desire to provide wider paved roadways gave Kossuth County the additional incentive needed to proceed with a pavement recycling project.
Resumo:
Kossuth County is located in North Central Iowa bordering on the State of Minnesota. It is the largest county in Iowa consisting of 28 congressional townships. The population of the county is 23,000 of which 11,000 people live in the rural area. There are 13 towns located in the county with the county seat, Algona, being the largest with a population of 6,100. Major industry of the area is grain farming with some beef and hog production. Naturally, where there is good grain farm land it follows that there is poor soil available for road construction and pavements. However, below the 3 to 4 feet of good farm land of Kossuth there is present a good grade of clay soil which does make an adequate base for surfacing when placed and compacted on top of the roadbed. As early as 1950, the then Kossuth County Engineer, H.M. Smith, embarked on a program of stage construction in building new grades and pavements. The goal of his program was primarily to conserve the county's rapidly dwindling supply of surfacing materials, and also, to realize the side effects of providing smooth and dustless roads for the public. Engineer Smith was fully aware of the poor soils that existed for road construction, but he also knew about the good clay that lay below the farm soil. Consequently, in his grading program he insisted that road ditches be dug deep enough to allow the good clay soil to be compacted on top of the roadbed. The presence of the compacted clay on top of the road resulted in a briding affect over the farm soil. The stage construction program satisfied the objectives of aggregate construction and dust control but did generate other problems which we are now trying to solve as economically as possible.
Resumo:
The relationship between Iowa’s roads and drainage developed when rural roads were originally constructed. The land parallel to roadways was excavated to create road embankments. The resulting ditches provided an outlet for shallow tiles to drain nearby fields for farming. Iowa’s climate and terrain are nearly ideal for farming, and more than 90 percent of the land suits the purpose. Much of the land, however, needs to be artificially drained to achieve maximum productivity. Most of this drainage has been accomplished with an extensive network of levees, open ditches, and underground tiles. The U.S. Census Bureau estimated that as early as 1920 approximately nine million acres of Iowa farm land had been artificially drained or needed to be. Couple this drainage system with Iowa’s extensive surface transportation system—approximately 100,000 miles of roads and streets, 90,000 on local systems— and potential for conflicts will naturally arise. This is particularly true with urban expansion resulting in residential and commercial development of rural land. This manual contains summaries of and references to the laws most relevant to drainage in Iowa. It also includes frequently asked questions about transportation agencies’ responsibilities related to drainage. Typical policies and agreement forms used by agencies to address drainage issues are illustrated and a glossary of common terms is included.
Resumo:
Silver Lake is located in an 18,053-acre watershed. The watershed is intensively farmed with almost all of the wetlands being previously drained or degraded over the last 50 years. Silver Lake is listed on the State of Iowa’s impaired water bodies list due to sediment and high nutrient level. Silver Lake is also known be in the bottom 25 percentile of Iowa’s lakes due Secchi disk readings and Chlorophyll a level. Farming in the watershed is the principle concern and cause for many of the problems occurring in Silver Lake currently with 78% of the watershed being intensively farmed. There are two major drainage ditches that have been used to drain the major wetlands and sloughs that, at one time, filtered the water and slowed it down before it reached Silver Lake. With these two major drainage ditches, water is able to reach the lake much faster and unfiltered than it once did historically. The loss of 255 restorable wetland basins to row crop production has caused serious problems in Silver Lake. These wetland basins once slowed and filtered water as it moved through the watershed. With their loss over the last 50 years that traditional drainage no longer occurs. We propose to create a Wetland Reserve Program incentive project to make WRP a more attractive option to landowners within the watershed. The incentive will be based on the amount of sediment delivery reduction to the lake, therefore paying a greater payment for a greater benefit to the lake. The expected result of this project is the restoration of over 250 acres of wetland basins with an associated 650 acres of upland buffers. The benefit for these wetlands and buffers would be reduced sediment, reduced nutrients, and slowed waters to the lake.
Resumo:
A water quality resource concern has come to the forefront in the Upper Miller Creek watershed in Black Hawk County after five to seven inches of rain fell on the area on May 22nd and 23rd of 2004 and unprecedented amounts of soil and organic debris were washed from cultivated areas, clogging most culverts and roadside ditches. The quantity of soil deposited in ditches gave a good indication of the amounts that were transported into the stream. The estimated total cost to Black Hawk County for cleanup and repair within the road right-of-way was $345,000. There were undetermined environmental costs incurred when the incredibly high volumes of soil washed from the fields into Miller Creek which flows directly into the Cedar River that is identified by the Department of Natural Resources as an impaired water body. The Upper Miller Creek Watershed Project is an innovative, collaborative project intended to meet a specific need identified by a local steering committee made up of concerned community agencies and local landowners. Led by the Soil and Water Conservation District and the Black Hawk County Board of Supervisors, the Miller Creek Watershed Project seeks to reduce soil erosion, improve water quality, and reduce county road infrastructure cost by implementing conservation practices, reducing nutrient and pesticide use and improving wildlife habitat.